1. Field of the Invention
The invention relates to a sealing ring for a dry running piston rod.
2. Description of the Prior Art
Sealing rings are usually arranged pairwise one behind the other in series and form in this manner a so-called packing. The pressure difference acting on the individual sealing rings causes their sealing surfaces to be pressed onto the sliding surfaces of the body to be sealed, for instance, a piston rod. Such sealing rings are known, for example, from the patent CH 439 897. These known sealing rings have the disadvantage that the sealing surfaces pressed against the sliding surface cause a strong heat of friction, which leads to overheating and rapid wear. This is true, in particular, for the use of sealing rings in dry running piston compressors which manage in the compression part without any foreign lubrication. Compressors of this type have fixed sealing rings past which a piston rod is moved.
The object of the present invention is to propose a sealing ring suitable for dry running apparatuses and having an improved sealing behavior.
The sealing ring in accordance with the invention has a height H in the axial direction as well as a surface oriented towards the dry running sliding surface of the body to be sealed off, which is executed in such a manner that it extends parallel to the sliding surface over a portion of the height H and thus forms a sealing surface. The remaining portion of the height H of the sealing ring is spaced from the sliding surface.
In an advantageous embodiment of the sealing ring in accordance with the invention, the remaining portion of the height H of the sealing ring, which does not lie in contact with the sliding surface, is made conically divergent.
The sealing ring is to be arranged in a dry running piston compressor, in particular, with respect to the piston rid in such a manner that the conically divergent region is oriented towards the cylinder space and diverges in the direction towards the cylinder space. A sealing ring of this type has the advantage that the sealing surface of the sealing ring lying in contact with the piston rod is relatively small, which results in reduced friction. A further advantage of the embodiment of the surface in accordance with the invention is to be seen in the fact that through its shape in combination with the reduced sealing surface the gas attempts to flow between the sealing surface and the piston rid so that a gas bearing arises between the sealing surface and the piston rod. Such a gas bearing has the advantage that the friction between the piston rod and the sealing surface is further reduced.
A sealing ring of this kind in accordance with the invention can, in particular, be advantageously used when the fixed seal elements have a high sealing action in the axial direction so that a gas bearing arises, because a large part of the gas flows out between the piston rod and the sealing surface.
The design of the surface oriented towards the sliding surface in the axial direction can be realized in a number of embodiments in such a manner that the surface of a first partial region has a surface extending parallel to the sliding surface and a second partial region has a surface spaced from the sliding surface.
The sealing ring in accordance with the invention is suitable, in particular, for sealing dry running piston compressors operating under very high pressure.